Estimation of Acentric Factor of Organic Compounds with Corresponding States Group Contribution Method

A new estimation method was proposed by combining the corresponding state principle with the group contribution method through introducing the concept of assumed-critical properties. Combining it with the Reidel equation, a new acentric factor correlation equation (CSGC-Reidel) was developed. Contribution values of 70 groups were obtained by correlating acentric factor data of 228 organic compounds of 14 type substances including saturated hydrocarbons, unsaturated hydrocarbons, cyclanes, aromatics, oxygen compounds, nitrogen compounds,halohydrocarbons, etc. The average error of acentric factor is 3.52% between the literature data and the predicated with the new estimation method.

A Perfect Shape Factor Corresponding States Principle for Pure Non-Polar and Polar Fluids

In the two-parameter corresponding states principle(CSP), the critical compressibility factors of the fluid under study(called 'a' fluid) and the reference fluid(called 'o' fluid) must be identical. This is not generally observed in nature. To overcome this limitation, a perfect shape factor CSP is proposed in which the compressibility factors of 'a' and 'o' fluids are corresponded perfectly by introducing a new pressure shape factor 8. Using methane as the 'o' fluid, the shape factors of many fluids are calculated from PVT properties at saturation state and the second virial coefficients. Models are also formulated for the shape factors with the assumption of is a function of temperature and volume while 6 and 5 are temperature dependent only. The models described the shape factors satisfactorily in whole region including vapor, liquid and their co-existing phases. The perfect shape factor CSP could be applied for both polar and non-polar fluids.

An Improved Prediction Equation of Refrigerants Surface Tension Based on the Principle of Corresponding States

The surface tensions of 21 pure refrigerants have been predicted by a new improved equation based on the principle of corresponding states with double referenced fluids.The average absolute deviation between the calculated surface tensions from the equation and the experimental result is-0.015 mN/m.The surface tensions of 9 binary mixtures were calculated in consideration of certain mixing rules.And the average absolute deviation between the calculated surface tensions from the equation and the experimental result is-0.251 mN/m.The new improved prediction equation can be used for calculating the surface tension of environmental friendly refrigerants.

Extended law of corresponding states for percolation threshold of short-range attractive spheres

The percolation threshold(PT)for colloidal system refers to the point at which particles aggregate to form an infinite cluster that spans the suspension[1].It is widely assumed that the percolation transition should follow the concept of scaling,and recent numerical studies[2-5]have shown that the wrapping probability of percolation can be described by the universal scaling functions,which enables the estimation of PTs for different types of system.

Calculation of Transport Properties of CF4＋Noble Gas Mixtures

The present work is concerned with determining the viscosity,diffusion,thermal diffusion factor and thermal conductivity of five equimolar binary gas mixtures including:CF4-He,CF4-Ne,CF4-Ar,CF4-Kr,CF4-Xe from the principle of corresponding states of viscosity by the inversion technique.The Lennard-Jones (12-6) model potential is used as the initial model potential.The calculated interaction potential energies obtained from the inversion procedure is employed to reproduce the viscosities,diffusions,thermal diffusion factors,and thermal conductivities.The accuracies of the calculated viscosity and diffusion coefficients were 1% and 4%,respectively.

Determination of Transport Properties for Dilute Gas Mixtures Involving Carbon Tetrafluoride

In our previous work,we calculated transport properties of pure gaseous polyatomic carbon tetrafluoride(CF4) and five equimolar binary gas mixtures of CF4 with noble gases through inversion technique.The present work is a continuation of our studies on determining the transport properties of binary gas mixtures CF4 with some gases including three diatomic molecules CO,N2,and O2,a linear polyatomic CO2,and two non-linear polyatomic molecules SF6 and CH4.The Chapman-Enskog and Vesovic-Wakeham methods as well as inversion procedure are used to determine the viscosities,diffusivities,and thermal conductivities,which deviates from the literature values within 1%,4%,and 5%,respectively.